1. Field of the Invention
The present invention relates to a communication configuration for debugging, respectively for programming one or more participants of the communication configuration, as well as to a corresponding method.
2. Description of the Related Art
Many networks employ serial interfaces instead of parallel interfaces. This is done to reduce the costs of assembly and connection technology, for example, the number of pins, to simplify the system design, and to provide bandwidth scalability of transmission data through the parallel use of a plurality of serial interfaces.
This trend is manifested in the field of consumer electronics, in particular, by a multitude of serial interface standards. These are mostly used for communicating with peripheral devices, such as hard disks or displays. However, apart from the small number of pins, these interfaces use complex protocols that require a significant outlay for implementation. Today's interfaces require several data streams, such as PCI Express or QuickPath, and thereby provide a bandwidth scalability for the system designer to transmit data among logic modules (ICs), for example, on the main board of a PC or within a handheld device.
In the field of automotive technology, serial interfaces (SPI, serial peripheral interfaces) are used for transmitting data among logic modules that are configurable as integrated circuits (IC, integrated circuits) in control units. This standard describes a bidirectional, synchronous and serial data transmission between a module configured as a master and various modules configured as slaves. An interface includes at least three lines between the master and a slave. These are typically two data lines and one clock line. If there are a plurality of slaves, each of these modules requires an additional select line from the master. The SPI interface makes it possible to implement a daisy-chain or bus topology.
In some cases, the SPI interface is not suited for transmitting the time-critical drive signals that are needed to meet the real-time requirements of today's safety-critical applications, such as ESP. Often, the use of an SPI interface merely entails exchanging diagnostic and status information. Due to the use of timer units and/or proprietary interfaces, substantial outlay is generally required to transmit time-critical drive signals to the drive modules of the actuators and/or from the evaluation circuits of the sensors.
When the SPI interface is used in the form of a bus topology at higher data rates, poor EMC properties cause worsening signal integrities and significant interference. In addition, only the transmission signal is transmitted in synchronism with the clock signal, while, at high data rates, the phase-synchronous transmission of the received signal becomes increasingly more difficult due to the internal delay times in the slave. It can also cause errors in the data transmission.
Very long latency times arise when the SPI interface is used in a daisy-chain topology, i.e., ring topology, which is why this form cannot be efficiently used in motor vehicle control units.
Published German patent application document DE 10 2010 041 427 describes a communication configuration which has significant advantages over the known configurations. This communication configuration has an annular configuration (preferably a daisy-chain topology) and includes at least two participants that are serially interconnected (preferably via point-to-point connections). The participants include one master, as well as one or a plurality of slaves. Each of the slaves has a shift register, preferably a 1-bit shift register. This allows data to be transmitted via the communication configuration, thus over the ring, from participant to participant with a minimal delay of one bit.
Besides the interchip interfaces in question, the related art provides a separate interface (for example, JTAG) for the debugging and/or programming of the control units that is no longer accessible following shipment of the control units. However, it is also possible to program a new software or to read out measurement data from the control units via external communication interfaces (for example, CAN), however, using a limited bandwidth in comparison to a dedicated interface approach.
A method for an in-system programming using SPI and JTAG is known from U.S. Pat. No. 7,265,578 B1, for example. U.S. Pat. No. 7,554,357 B2 describes an efficient programming of participants of a daisy-chain configuration.